What are the advantages of using CA IDMS/DB Reorg over the Unload/Reload utilities?
Both of these utilities provide tuning, restructuring and reorganization of all or part of a CA IDMS database. Determining which of the utilities is appropriate in a given situation will depend upon the database characteristics, size, and familiarity of the DBA with the utilities.
DB/Reorg has the following advantages:
- It allows more direct control over the placement of records in the target database. The PRIORITY parameter of DB/Reorg allows you to specify the order in which records will be assigned to target pages.
- Is fully restartable from any of its individual steps using the STOPAFTER and RESTART parameters. This planned pause during reorganization steps may help in disk space management.
- It can create an interface file for use with the DB-EZReorg inflight reorganization product.
- Automatically deletes LDEL (logically deleted) records in areas that are being copied. This means you do not have to use another utility prior to running DB/Reorg for LDEL elimination.
- It allows you to alter location mode of a record and to expand or reduce the number of index table entries by changing the size of the associated SR8 record.
Since DB/Reorg runs a single program, it may require a much larger region/partition size than Unload/Reload, so it may not be suitable if space is a concern. DB/Reorg also requires that certain work files be preallocated as VSAM or BDAM, involving a more detailed set-up.
The execution time for both utilities depends on the size of the areas, the number of records and the number of set linkages for each of these areas.
There is no simple method to determine which utility will take less time to run.
CA IDMS/DB Reorg User Guide
CA IDMS Utilities Guide sections UNLOAD and RELOAD